Marine Geophysics and Hydroacoustics

NW Africa

Summary

The passive margin off NW-Africa is investigated by the workgroup since a long time; it is shaped by a complex interplay of sediment transport processes, directed both downslope and alongslope. During several cruises, sediment transport processes between 12° and 29°N off Senegal, Mauritania, and Western Sahara were investigated by means of geophysical and sedimentological methods. Sediment transport on the Northwest African continental margin operates with different rates and styles: some sections of the margin show a large concentration of upper slope canyons but no indication for significant mass wasting, whereas other sections are characterized by large-scale mass wasting with no canyons or gullies. Four mega-slides, each affecting over 20,000 km2 of seafloor, have been identified along the continental slope off Northwest Africa. All slides are complex in morphology and show a stepped headwall pattern typical for retrogressive failure. Several buried mass transport deposits are seismically imaged beneath all near-surface slides indicating a long history of mass wasting for some sections of the margin.More...

Bathymetrie des Agadir-Canyons

Bathymetry of Agadir Canyon, recorded during cruise MSM32.

Additional activities of the working group were carried out as preparation for a drilling campaign proposed to the International Ocean Discovery Program. Main objectives of the IODP proposal ‘‘Cenozoic climate, productivity, and sediment transport at the NW African continental margin’ are: i) NW African climate in a warmer world, and ii) High productivity ecosystem response to climates different from today. Sediment cores should be retrieved in six areas off NW-Africa. The suggested sites have been mainly selected based on seismic investigations of the working group. The latest investigations were carried out on the Cape Verde Plateau during Cruise MSM87. The aim was to identify a site, where Miocene sediments can be drilled at relatively shallow subsurface depth.

 

Seismic section recorded durring MSM87 showing SIte NWAFR-14A.

Seismic section recorded durring MSM87 showing Site NWAFR-14A.
 

 

Contact for this project:  Sebastian Krastel

Scientific Cruises:

  • FS Maria S. Merian - MSM87: Seismic pre-site survey for the International Ocean Discovery Program (IODP) on the Cape Verde Plateau offshore NW Africa. November 17th - November 25th, 2019
  • FS Maria S. Merian - MSM82/2: Morphology of the headwall area of the Sahara slide, NW-Africa, April 26th - May 14th, 2019
  • FS Maria S. Merian - MSM32: Morphology, processes and geohazards of giant landslides in and around Agadir Canyon, northwest Africa, Sept. 25th - Oct. 30th, 2013
  • FS Poseidon - P395: Sahara Slide Complex, February 4th - 19th, 2010
  • FS Maria S. Merian - MSM11: Pre-Site Survey for an IODP cruise Neogene Paleoclimate and sediment transport at the continental margin of NW Africa, March 14th - April 9th, 2009
  • FS Meteor - M65/3:  Climate History and Sedimentation Processes off NW Africa, June 11th - August 10th, 2005

Most relevant publications:

  • Li W., Alves, T.M., Urlaub, M., Georgiopoulou, A., Klaucke, I., Wynn, R.B., Gross, F., Meyer, M., Repschläger, J., Berndt, C., Krastel, S. (accepted for publication in Marine Geology) Morphology, age and sediment dynamics of the upper headwall of the Sahara Slide Complex, Northwest Africa: Evidence for a large late Holocene failure
  • Krastel, S., Wynn, R.B., Feldens, P., Schürer, A., Böttner, C., Stevenson, C., Cartigny, M., Hühnerbach, V., Unverricht, D. (2016) Flow behaviour of a giant landslide and debris flow entering Agadir Canyon, NW Africa. In: Submarine mass movements and their consequences (eds: Lamarche, G. et al). Advances in Natural and Technological Hazards Research, 41, Springer, 145-154.
  • Glogowski, S., Dullo, W.-C., Feldens, P., Liebetrau, V., von Reumont, J., Hühnerbach, V., Krastel, S., Wynn, R.B., Flögel, S. (2015) The Eugen Seibold coral mounds offshore western Morocco: oceanographic and bathymetric boundary conditions of a newly discovered cold-water coral province. Geo-Marine Letters, 25, 257-269, DOI: 10.1007/s00367-015-0405-7
  • Krastel, S., Lehr, J., Winkelmann, D., Schwenk, T., Preu, B., Strasser, M., Wynn, R.B., Georgiopoulou, A., Hanebuth, T. (2014) Mass wasting along Atlantic continental margins: a comparison between NW-Africa and the de la Plata River region (northern Argentina and Uruguay). In: Submarine mass movements and their consequences (eds: Krastel et al). Advances in Natural and Technological Hazards Research, 37, 459-469.
  • Krastel, S., Wynn, R.B., Georgiopoulou, A., Geersen, J., Henrich, R., Meyer, M., Schwenk, T. (2012) Large scale mass wasting at the NW-African Continental Margin: some general implications for mass wasting at passive continental margins. Submarine mass movements and their consequences. In: Yamada, Y. et al. (eds), Advances in Natural and Technological Hazards Research, 31, Springer, 189-199.
  • Meyer, M., Geersen, J., Krastel, S., Schwenk, T., Winkelmann, D. (2012) Dakar Slide offshore Senegal, NW-Africa: Interaction of stacked giant mass-wasting events and canyon evolution. Submarine mass movements and their consequences. In: Yamada, Y. et al. (eds), Advances in Natural and Technological Hazards Research, 31, Springer, 177-188.
  • Pierau, R., Henrich, R., Preiß-Daimler, I., Krastel, S., Geersen, J. (2011) Sediment transport and turbidite architecture in the submarine Dakar Canyon off Senegal, NW-Africa. Journal of African Earth Sciences, 60, 196-208.
  • Georgiopoulou, A., Masson, D., Wynn, R.B., Krastel, S. (2010) The Sahara Slide: Initiation and processes from headwall to deposit of a giant submarine slide. G-cubed. 11-7. doi:10.1029/2010GC003066.